1. Field of the Invention
The present invention relates to an imaging apparatus, and more particularly, to an optical image imaging apparatus or imaging apparatus that is used for ophthalmological diagnosis and treatment or the like.
2. Description of the Related Art
A scanning laser ophthalmoscope (SLO) which uses a principle of a confocal laser microscope is an ophthalmological apparatus that performs a raster scanning on a fundus of the eye with laser light which is measuring light and obtains a planar image of the fundus of the eye based on the intensity of return light with high resolution at high speed.
Such an apparatus for photographing or imaging a planar image is hereinafter referred to as SLO apparatus.
In recent years, it has become possible to acquire a planar image of a retina with improved lateral resolution by increasing a beam diameter of measuring light in the SLO apparatus. However, along with the increase in the beam diameter of measuring light, there occurs a problem of decreases in an SN ratio and the resolution of a planar image of a retina due to an aberration of an eye to be inspected when the planar image is acquired.
In order to solve the problem, there is developed an adaptive optics SLO apparatus including an adaptive optics system, in which an aberration of an eye to be inspected is measured by a wavefront sensor in real time, and aberrations of measuring light and return light thereof generated in the eye to be inspected are corrected by a wavefront correction device. Thus, it is possible to acquire a planar image with high lateral resolution.
When a planar image with high lateral resolution is acquired, because of problems of optical aberrations of the apparatus itself and a longer imaging time, an imaging range of a single image becomes smaller. As a result, there is a tendency that it becomes difficult to distinguish which part of the fundus the planar image corresponds to. In Japanese Patent Application Laid-Open No. 2010-259543, there is proposed a complex apparatus in which an SLO apparatus having a large field angle and an SLO apparatus having a small field angle with high resolution are combined so as to solve the problem.
When the aberration of the eye to be inspected is corrected by the wavefront correction device, the aberration of the device itself or its optical system may become a problem. In Japanese Patent Application Laid-Open No. 2008-161406, a mechanism for correcting a very small spherical aberration generated by an adaptive optics system is disposed so that a clear fundus image can be acquired.
As the fundus imaging apparatus described in Japanese Patent Application Laid-Open No. 2010-259543, as described above, the complex apparatus is proposed, in which the SLO apparatus having a large field angle and the SLO apparatus having a small field angle with high resolution are combined. Thus, a high resolution fundus image can be acquired efficiently.
In addition, in the ophthalmological apparatus described in Japanese Patent Application Laid-Open No. 2008-161406, the mechanism for correcting a very small spherical aberration generated by the adaptive optics system is disposed as described above, and hence a clear fundus image can be acquired.
Here, a measurement range of the wavefront sensor is determined in assumption of high ametropia (for example, −10 D to +5 D). In the case of Shack-Hartmann sensor that is a typical wavefront sensor, the measurement range and measurement accuracy have a trade-off relationship in principle. Therefore, the measurement accuracy is low in the case of low ametropia. In the conventional technologies described in Japanese Patent Application Laid-Open No. 2010-259543 and Japanese Patent Application Laid-Open No. 2008-161406, the aberration of the eye to be inspected, and the measurement range and measurement accuracy of the wavefront sensor are not taken into account, and hence there is a room for improvement.